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arXiv · 1801.06952

Order from chaos: Observation of large-scale flow from turbulence in a two-dimensional superfluid

Shaun P. Johnstone·Andrew J. Groszek·Philip T. Starkey·Christopher J. Billington·Tapio P. Simula·Kristian Helmerson
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Abstract

Interacting systems driven far from equilibrium tend to evolve to steady states exhibiting large-scale structure and order. In two-dimensional turbulent flow the seemingly random swirling motion of a fluid can evolve towards persistent large-scale vortices. Lars Onsager proposed a model based on statistical mechanics of quantized vortices to explain such behavior. Here we report the first experimental confirmation of Onsager's model of turbulence. We drag a grid barrier through an oblate superfluid Bose--Einstein condensate to generate non-equilibrium distributions of vortices. We observe an inverse energy cascade driven by the evaporative heating of vortices, leading to steady-state configurations characterized by negative temperatures. Our results open a pathway for quantitative studies of emergent structures in interacting quantum systems driven far from equilibrium.

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Shaun P. Johnstone, Andrew J. Groszek, Philip T. Starkey, Christopher J. Billington, Tapio P. Simula, Kristian Helmerson. 2018-01-22. Order from chaos: Observation of large-scale flow from turbulence in a two-dimensional superfluid. https://doi.org/10.1126/science.aat5793

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